ET ATT WEEK 13 | ACTUAL COMPLETE QUESTIONS AND ANSWERS | DEFINED ACCURATE | 2025 UPDATE.

ET ATT WEEK 13 | ACTUAL COMPLETE
QUESTIONS AND ANSWERS | DEFINED
ACCURATE | 2025 UPDATE.

Q: What are the characteristics of AM (Amplitude Modulation)?
ANSWER ✔✔ Amplitude changes (intel is in amplitude), frequency stays the same
Contains:
a. Original Carrier Frequency
b. Modulation Signal
c. Sum of the carrier and modulation signal
d. Difference of the carrier and modulating signals



Q: What components make up an AM receiver?
ANSWER ✔✔

1. RF Section
2. Mixer
3. LO (Local Oscillator)
4. IF Amplifier
5. AM Detector
6. AGC (Automatic Gain Control)
7. AF Amplifier



Q: What does AGC (Automatic Gain Control) do?
ANSWER ✔✔ Automatically controls amplitude increase from original input to amplified
output.
Eliminates fluctuations in the output when the RF input varies.



Q: What is the formula for Modulation Percentage?
ANSWER ✔✔ % Mod = (Vmax - Vmin) / (Vmax + Vmin) × 100



Q: What is Heterodyning?
ANSWER ✔✔ Changes a signal's frequency without changing the signal's intelligence.

, Q: What do heterodyned signals contain?
ANSWER ✔✔

1. Original RF Signal
2. Original LO Signal
3. Sum of the RF and LO signals
4. Difference of the RF and LO signals



Q: What does a mixer do in a receiver?
ANSWER ✔✔ Mixes the carrier signal and LO signal to produce IF (Intermediate Frequency).



Q: What is the standard IF for AM and FM receivers?
ANSWER ✔✔

 AM: 455 kHz
 FM: 10.7 MHz



Q: What is synthesized tuning?
ANSWER ✔✔ Uses a lower reference frequency (usually from a PLL) to create a wide range of
high frequencies.



Q: What is a PLL (Phase Locked Loop)?
ANSWER ✔✔ A circuit that constantly adjusts to match an input frequency and helps filter
noise.



Q: What components make up a PLL?
ANSWER ✔✔

1. Phase Detector
2. Frequency Counter/Divider
3. VCO (Voltage Controlled Oscillator)
4. Loop Filter